Mjolnir, Thor's hammer.

thingiverse

Swedish style Thor's hammer Mjolnir: Mjolnir, The Crusher, possibly represents the beating heart and general life force. It likely evolved from the axe of Perun, which in turn may have originated from a flint arrowhead or stone axe. The sun cross symbolizes the sun and the four seasons. Valknut/Hrungnir's Heart: The theory that it represents a proud heart is preferred, referencing the story of Hrungnir. Additional triangular shapes have been discovered on various Viking Age Mjolnir pendants.